1. Field of the Invention
This invention relates to a serpentine type evaporator for use in a space cooling cycle such as in an automotive air-conditioning system, and more particularly to improvements in and concerning a header pipe on the outlet side of the evaporator.
2. Description of Prior Art
Generally, the cooler unit of the automotive air-conditioning system incorporates therein an evaporator which forms part of the space cooling cycle.
Among the conventional evaporators of this class is counted a serpentine type evaporator constructed as shown in FIG. 1. The serpentine type evaporator comprises a serpentine tube 1 of a flat cross section containing a plurality of coolant conduits 2 and corrugated in a zigzag pattern, fins f interposed between each pair of opposed outer surfaces 3 of the serpentine tube 1, and an inlet side header pipe 4 and an outlet side header pipe 5 connected to the opposite ends of the serpentine tube 1 in such a manner that their interiors communicate with the interiors of the group of coolant conduits 2. Through the inlet side header pipe 4, the coolant which has been given decreased pressure and rendered more susceptible to evporation in an expansion valve flows into the group of coolant conduits 2 in the serpentine tube 1. During the travel through the group of coolant conduits 2 shaped in a smimlarly corrugated form, the coolant deprives the air flowing between the fins f of heat and evaporates, with the result that the heat of this evaporation cools the air. The gaseous coolant resulting from the evaporation is forwarded through the outlet side header pipes 5 into a compressor which is not shown in the diagram.
The serpentine type evaporator by nature is disposed to send off vibratory noise, though feebly, while in operation. Our investigation into the cause for this noise has uncovered the fact that at the time the coolant spurts from the coolant conduits 2 of the serpentine tube 1 into the outlet side header pipe 5, as illustrated in FIGS. 2 and 3, edge noise occurs in the neighborhood of E portion of the tube outlet end and standing current A occurs in the neighborhood of the closed end of the outlet side header pipe 5. Owing to this standing current A, the noise is generated within the outlet side header pipe of the shaped tube 1. Particularly in the case of automobiles of latest models, since their interiors are kept in deep silence by use of tight seals, it is desirable that the noise of the cooler unit including the evaporator which is installed in the automobile interior should be precluded at all cost.
An object of this invention, therefore, is to provide an improved serpentine type evaporator.
Another object of this invention is to provide a serpentine type evaporator adapted to curb the occurence of the standing current within the outlet side header pipe and consequently prevent the occurence of the resonance noise.
Yet another object of this invention is to provide an improved serpentine type evaporator to be incorporated in the space cooling cycle of the air-conditioning system as in the automobile.